Pulmonary Fibrosis is a term used to describe the accumulation of scar tissue around the air spaces of the lung. This often gets worse with time and leads to progressively breathlessness and other symptoms such as cough. Sadly many patients eventually die from their pulmonary fibrosis. When pulmonary fibrosis is fairly advanced, it may can be seen on a simple chest X ray. However, in many cases the chest X ray can look normal but abnormailities will be seen on a CT scan (‘CAT scan’) of the lungs. The part of the lung where scar tissue accumulates is called the interstitium of the lung. Respiratory doctors often use the term interstitial lung disease (ILD) instead of pulmonary fibrosis.
We know that some types of pulmonary fibrosis can be caused by exposure to envronmental dusts and particles, by some drugs or by radiation. Some people can have pulmonary fibrosis as part of a condition like rheumatoid arthritis or ‘connective tissues disease’. In other people there is no clear cause, a condition that doctors refer to as idiopathic. Unfortunately there are lots of different types of pulmonary fibrosis and the terms can be confusing, even to general respiratory consultants who do not specialise in interstitial lung disease.
One very confusing aspect of the terminology is that specialists use the diagnostic label Idiopathic Pulmonary Fibrosis (IPF) for a very specific subtype of patients with pulmonary fibrosis of no known cause. You can find out more about this on the IPF page. The reason this is important is that in the last few years specialists have shown that two drugs, pirfenidone (Esbriet™) and nintedanib (Ofev™), have a beneficial effect on patients with Idiopathic Pulmonary Fibrosis. To date there have been no good trials showing a beneficial response to treatments of other types of pulmonary fibrosis.
Traditionally doctors have tended to give patients with pulmonary fibrosis corticosteroids (‘steroids’) such as prednisolone. Prednisolone can have undesirable side effects such as weight gain. Other drugs included so-called ‘steroid-sparing’ agents like azathioprine and agents that targetted cell damage caused by oxgen and related chemicals (antioxidants). The most commonly used antioxidant is called N-acetyl cysteine (NAC). For a few years many specialists believed that so-called ‘triple therapy’ with prednisolone, azathioprine and NAC was the right treatment for Idiopathic Pulmonary Fibrosis. Disturbingly, but crucially, a major trial comparing triple therapy with NAC alone or with placebo (the PANTHER-IPF trial) closed rectruitment early in 2012 when an interim analysis showed that patients on triple therapy did worse than those on placebo (dummy tablets with no active ingredient). This episode emphasises the importance of performing properly-designed trials in pulmonary fibrosis.
Despite the results of the PANTHER-IPF trial in IPF, doctors still sometimes use drugs like steroids and steroid-sparing agents in other types of ILD, particularly when the pulmonary fibrosis occurs in the context of connective-tissue disease. You can read about the treatment of these conditons here and about the other types of ILD here.